Fan simulation circuit

ABSTRACT

A fan simulation circuit includes a connector, a voltage converter, a control chip, and a selecting module. The connector is used to output a speed signal. A power pin of the voltage converter is connected to a first voltage input terminal An output pin of the voltage converter is connected to a speed pin of the connector through a first resistor. The output pin is also connected to a second voltage input terminal through the first resistor and a second resistor in that order. The selecting module is used to output high or low-level signals to the control chip. The control chip outputs different speed signals to an input pin of the voltage converter. The voltage converter converts the speed signals and outputs converted speed signals to the speed pin of the connector.

BACKGROUND

1. Technical Field

The present disclosure relates to a circuit for simulating fans.

2. Description of Related Art

A fan monitor board is used to monitor rotational speeds of fans of aserver. When testing the fan monitor board, the fan monitor board mustreceive speed signals from the fans. However, not all fans can outputspeed signals, so it may be difficult to test the fan monitor board.

Therefore, there is room for improvement in the art.

BRIEF DESCRIPTION OF THE DRAWING

Many aspects of the present disclosure can be better understood withreference to the following drawing(s). The components in the drawing(s)are not necessarily drawn to scale, the emphasis instead being placedupon clearly illustrating the principles of the present disclosure.Moreover, in the drawing(s), like reference numerals designatecorresponding parts throughout the several views.

The FIGURE is a circuit diagram of an embodiment of a fan simulationcircuit of the present disclosure.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean “at least one.”

The FIGURE shows an embodiment of a fan simulation circuit 10 of thepresent disclosure.

The fan simulation circuit 10 comprises a connector J1, a voltageconverter U1, a control chip U2, and a selecting module SW. The fansimulation circuit 10 is arranged on a fan monitor board. The fanmonitor board receives speed signals output by the fan simulationcircuit from a speed pin TACH of the connector J1.

A power pin VCC of the voltage converter U1 is connected to a firstvoltage input terminal P5V. An output pin OUT of the voltage converterU1 is connected to a second voltage input terminal P12V through a firstresistor R1 and a second resistor R2 in that order. A node between thefirst resistor R1 and the second resistor R2 is connected to the speedpin TACH of the connector J1. A ground pin GND of the connector J1 isgrounded. A ground pin GND of the voltage converter U1 is grounded. Asignal output pin RA1 of the control chip U2 is connected to an inputpin IN of the voltage converter U1. A power pin VPP of the control chipU2 is connected to the first voltage input terminal P5V through aseventh resistor R7. A ground pin VSS of the control chip U2 isgrounded.

The selecting module SW comprises switches K1, K2, and K3. A first inputpin RB1 of the control chip U2 is grounded through the switch K1 and afourth resistor R4 in that order. The first input pin RB1 of the controlchip U2 is also connected to the first voltage input terminal P5Vthrough a third resistor R3. A second input pin RB2 of the control chipU2 is grounded through the switch K2 and a fifth resistor R5 in thatorder. The second input pin RB2 of the control chip U2 is also connectedto the first voltage input terminal P5V through an eighth resistor R8. Athird input pin RB3 of the control chip U2 is grounded through theswitch K3 and a sixth resistor R6 in that order. The third input pin RB3of the control chip U2 is also connected to the first voltage inputterminal P5V through a ninth resistor R9. The control chip U2 outputssignals indicating different speeds to the first input pin IN of thevoltage converter U1 corresponding to high or low level signals receivedby the first, second, and third input pins RB1, R2, and RB3. Operationvoltages of the connector J1 and of the control chip U2 are different.The voltage converter U1 converts the signals from the control chip U2and outputs the converted signals through the output pin OUT to theconnector J1.

In one embodiment, when the switches K1 and K2 are turned on and theswitch K3 is turned off, the first and second input pins RB1 and RB2receive low level signals, such as logic 0, and the third input pin RB3receives a high level signal, such as logic 1. The control chip U2outputs a first signal indicating a first speed to the voltage converterU1 through the first output pin RA1. The voltage converter U1 convertsthe first signal and outputs the converted first signal to the speed pinTACH of the connector J1. When the switches K1 and K3 are turned on andthe switch K2 is turned off, the first and third input pins RB1 and RB3receive the low level signals, and the second input pin RB2 receives thehigh level signal. The control chip U2 outputs a second signalindicating a second speed to the voltage converter U1 through the firstoutput pin RA1. The voltage converter U1 converts the second signal andoutputs the converted second signal to the speed pin TACH of theconnector J1. The fan monitor board receives the first and secondsignals from the connector J1 and displays the first and second speeds.The control chip U2 outputs signals indicating different speedscorresponding to signals received by the first, second, and third inputpins RB1, RB2, and RB3. Therefore, the fan simulation circuit 10 cansimulate fans operating at different speeds.

In one embodiment, the switches K1, K2, and K3 are toggle switches.Resistances of the fourth, fifth, and sixth resistors R4, R5, and R6 areabout 100 ohms Resistances of the third, eighth, and ninth resistors R3,R8, and R9 are about 10 kiloohms.

While the disclosure has been described by way of example andembodiments, it is to be understood that the disclosure is not limitedthereto. To the contrary, it is intended to cover various modificationsand similar arrangements as would be apparent to those skilled in theart. Therefore, the range of the appended claims should be accorded thebroadest interpretation so as to encompass all such modifications andsimilar arrangements.

What is claimed is:
 1. A fan simulation circuit, comprising: a connectorcomprising a speed pin; a control chip comprising a signal output pin, apower pin, a ground pin, and a plurality of input pins, wherein thesignal output pin of the control chip is connected to the speed pin ofthe connector, the power pin of the control chip is connected to a firstvoltage input terminal, the ground pin of the control chip is grounded;and a selecting module comprising a plurality of switches, wherein eachof the plurality of input pins of the control chip is grounded through acorresponding one of the plurality of switches, and is connected to thefirst voltage input terminal through a resistor, wherein the signaloutput pin of the control chip outputs signals indicating differentspeeds to the speed pin of the connector corresponding to signalsreceived by the plurality of input pins of the control chip.
 2. The fansimulation circuit of claim 1, further comprising a resistor connectedbetween each switch and ground.
 3. The fan simulation circuit of claim1, further comprising a voltage converter, wherein the voltage convertercomprises an input pin, an output pin, a power pin, and a ground pin,wherein the power pin of the voltage converter is connected to the firstvoltage input terminal, the output pin of the voltage converter isconnected to a second voltage input terminal through a first resistorand a second resistor in that order, a node between the first and secondresistors is connected to the speed pin of the connector, the ground pinof the voltage converter is grounded, the signal output pin of thecontrol chip is connected to the input pin of the converter, the voltageconverter converts the signals from the control chip and outputsconverted signals to the speed pin of the connector through the outputpin.
 4. A fan simulation circuit, comprising: a connector comprising aspeed pin; a control chip comprising a signal output pin, a power pin, aground pin, and an input pin, wherein the signal output pin of thecontrol chip is connected to the speed pin of the voltage converter, thepower pin of the control chip is connected to a first voltage inputterminal, the ground pin of the control chip is grounded; and aselecting module comprising a switch, wherein the input pin of thecontrol chip is grounded through the switch, and is connected to thefirst voltage input terminal through a resistor, wherein the signaloutput pin of the control chip outputs signals indicating differentspeeds to the speed pin of the connector corresponding to signalsreceived by the input pin of the control chip.
 5. The fan simulationcircuit of claim 4, further comprising a resistor connected between theswitch and ground.
 6. The fan simulation circuit of claim 4, furthercomprising a voltage converter, wherein the voltage converter comprisesan input pin, an output pin, a power pin, and a ground pin, wherein thepower pin of the voltage converter is connected to the first voltageinput terminal, the output pin of the voltage converter is connected toa second voltage input terminal through a first resistor and a secondresistor in that order, a node between the first and second resistors isconnected to the speed pin of the connector, the ground pin of thevoltage converter is grounded, the signal output pin of the control chipis connected to the input pin of the converter, the voltage converterconverts the signals from the control chip and outputs converted signalsto the speed pin of the connector through the output pin.